The principal objective of this research program is to elucidate the role of certain nucleoproteins, particularly structural proteins, at successive stages of mouse spermatogenesis. Initial emphasis will be directed toward, 1.) determining whether specific proteins, other than protamines, are displaced from the spermatozoan nucleus by Sarkosyl and varying concentrations of divalent cations, 2.) localizing the respective acidic and basic proteins to specific regions of the spermatozoan nucleus using monospecific monoclonal antibodies, 3.) examining the synthesis of chromosomal proteins during spermiogenesis, and, 4.) developing procedures for isolating an intact nuclear matrix with synaptonomal complexes from homogeneous populations of pachytene spermatocytes. The experimental approach to these problems will involve isolating homogeneous populations of the respective cell types and subcellular fractionation using established procedures (Bellve et al., 1975; Develop. Biol. 47, 349-365; Bellve et al., 1977, J. Cell Biol. 74, 68-85). Where pertinent monoclonal antibodies will be prepared by immunizing female mice with selected protein fractions and using the standard hybridoma technique to establish a stable cell line. Localization of antigens will be performed using light and ultrastructural immunological procedures in conjunction with the identification of antigens following polyacrylamide gel electrophoresis. The synthesis of chromosomal proteins during spermatogenesis is to be examined using (35S) methionine labeling in vivo and performing autoradiography after subjecting the polypeptides to two-dimensional polyacrylamide gel electrophoresis. Thus the various projects are designed to utilize morphological and biochemical procedures for resolving fundamental problems on the differentiation of the germ cell nucleus as it proceeds through meiosis and spermiogenesis.